Loudspeakers are a part of everyday life and used for consumer, commercial, military and research applications. The typical loudspeaker is an electro-dynamic transducer and has a diaphragm of some depth and diameter or shape. Electro-dynamic describes a transducer that moves in a positive and negative direction in response to a alternating voltage source to stimulate adjacent air molecules. At this point in time loudspeakers of this type are considered a commodity and are cheap and plentiful in supply. They are typically always mounted on a baffle as part of an existing product or structure; in some form of housing for practical containment or in some cases a form of specialized enclosure is utilized to enhance the bass performance. There are other types of electro-mechanical transducers in use generally exotic but most of which will benefit from the use of the Embedded Transmission Line Technology.
One of the greatest problems is the inherent nature of the driver to favor an acoustic impedance over a narrow range of frequencies relative to its' size. The smaller driver generally has unfavorable acoustical impedance for lower frequencies and vise versa for larger ones. The enclosure also favors a narrow range of frequencies and for others it reacts violently creating a plethora of incoherent internal standing waves that modulate the diaphragm with nonsymmetrical vibration patterns. These random internal modulations disturb the natural dispersion pattern of the driver and cause electrical feedback (reactance) to the amplifying source. Brute force power and heavy gauge wiring are current attempts to minimize this problem for the amplifier and the effects on sound quality. Another problem is the general acoustic impedance differential that exists on either side of the driver diaphragm. The diaphragm must work simultaneously in two different acoustic environments as the enclosure creates standing waves that constantly modify the drivers' acoustic impedance in most of its' frequency range. Reflected waves from the room cause additional modifications of the drivers' acoustic impedance more as the frequencies go lower towards that of the rooms' dimensions. Smaller enclosures are much worse because of the even higher frequencies that are reflected internally and the lack of low frequency capabilities. Two identical drivers will sound different due to their operating enclosure only. The industry has recognized the problem as one associated more with the mid-range speaker and has produced units with a solid basket behind the diaphragm. This may prevent random standing waves from the other drivers but it creates extreme backpressure for the range of frequencies produced by the midrange driver. This causes the driver to see a distinct acoustic impedance differential for all of its' operating range and not produce a natural sound.
Loudspeaker driver dimensions favor a certain range of frequencies thus making a single size for all frequencies an impossible task if wide axis listening is desired. It is a design goal to produce loudspeakers of the smallest dimensions necessary and maintain the proper loudness level while retaining the sonic presentation of full frequency range, low distortion, wide-constant dispersion and low cost. If one were to examine the situation it would appear to be a paradox requiring a compromise solution and the use of multiple drivers operating for a common acoustic purpose. This is reflected in the current loudspeaker design with theory compromised by art in an effort to produce subjectively accepted loudspeakers when the goal should be objectivity.
The requirement to use a single driver places a compromise solution favoring the lower or higher end frequencies while attempting to maintain quality in the middle ranges. The human ear tends to more sensitive to the higher frequencies but the human ear-brain combination prefers to hear all of the frequencies in the spectrum without phase or frequency aberrations to interrupt the flow of energy of the event otherwise it will appear to be artificial. The reproduction of sound is typically for either of two purposes and that is communication and entertainment. The latter requires unencumbered sonic balance and dispersion to balance the energy in the listening environment.
The continued efforts to perfect sound reproduction with predictable field results depend greatly on a solution to solve the dilemma of the enclosure. Engineers recognize the drivers' enclosure as a necessary evil or an opportunity to profit from the furniture created however the use of the enclosure as explained in the pending application provides a positive operating environment exposing the true quality of the driver. The result is elimination of the idiosyncratic behavior, objective sonic acceptance, simplified loudspeaker design and predictable results for varying acoustic situations.